@jrmat
The "jump scare" would be the docs jumping him when he scrambles back to the car. There I was thinking that it was pretty early for knifes in the back. It worked though.

To introduce the wife better you need to introduce the protagonist better. The moment you start showing us what and who he is you can slowly fade into memory lane.

But now that I know that you have just started writing my advice would be the following: stop worrying for now and have fun with your story first. Right now you are in deep “first draft” territory where most authors tell you to keep it hidden from the eyes of other people and even from the sun in the sky. Usually first drafts come out all wrong and deformed. But for what it’s worth right now you have two advantages, you are new to the craft and it is a first draft so that you are free to just go wild. I would suggest to keep writing and moving the story forward everything else will cost you a lot without yielding much.
Right now decide for a point of view that you want to follow for a while and stick to it. Gareth (right?) would be the best choice it is far easier to write an adult than a child, so that would be a great place to start. Right now he is running away, he is afraid and he wants to protect his daughter so these are the things that are first and foremost in his mind. Is he even returning home? (Doesn’t his wife know where they live?) What exactly is he afraid off? Also that fear is a good way to show how much he cares for his daughter.

You said that he is actually a bit of a coward that’s OK, but show it more. The scene in the garden with his wife and the knife was good where he stood petrified and was hoping his neighbours would call the police is a good example where we see what kind of man he is also it is a situation that feels very human. It is easy to empathise with him. That’s a good example of “show, don’t tell”.

Right now I think the biggest flaw is the motivation of the mother. Why if she did escape would she want to return home? And if she did why would she be aggressive towards husband and child? This needs to be addressed. But for now you have built enough momentum and seeing how the father thinks it is plausible enough that he is running away because he is taking no chances (reinforcing the idea that he is a bit of a coward) and you can worry about that later.

Use the momentum you’ve built, move forward and we’ll see what happens.